In a research project for the Naval Research Laboratory (NRL), in a report entitled "Fire Flicker Measurement Program," dated Dec. 24, 1985, Contract No. N0014-84-C-2262, David Sawyer first disclosed that open uncontrolled fires have a generalized flicker frequency spectrum where magnitudes of flicker-free frequencies are very high toward 0 Hz and then there is a steady decreasing trend. The foregoing was a theoretical analysis and no actual fire detection system was proposed.
In general, for a fire detection system it must inherently sense real fires and discriminate against false alarms of, for example, man-made origins such as various incandescent lights and blow torches; at the same time, because of the necessity of immediately extinguishing a real fire, long processing times for the information cannot be tolerated. But with shorter processing times, the information may inherently be less reliable and thus present systems have not solved these two opposing requirements.